Scientists have begun blurring the line between human and animal by producing chimeras—a hybrid creature that’s part human, part animal. 现在有一些科学家的研究开始混淆人类与动物的区别了，他们正在研究一种半人半兽的怪物。Chinese scientists at the Shanghai Second Medical University in 2003 successfully fused human cells with rabbit eggs. The embryos were reportedly the first human-animal chimeras successfully created. They were allowed to develop for several days in a laboratory dish before the scientists destroyed the embryos to harvest their stem cells. 2003年，上海二军大的科学家们成功地将人类体细胞植入兔子的耳朵中。这是有报道的最早关于人兽混合体的成功案例。这些成活的胚胎会在培养基内生长数天，直到研究者们摧毁并用其来提取干细胞In Minnesota last year researchers at the Mayo Clinic created pigs with human blood flowing through their bodies. 去年。明尼苏达州的Mayo诊所培育出了一只流着人类血液的猪。And at Stanford University in California an experiment might be done later this year to create mice with human brains.在加州的斯坦福大学，一个培育有人脑的老鼠的实验将于今年晚些时候完成Scientists feel that, the more humanlike the animal, the better research model it makes for testing drugs or possibly growing "spare parts," such as livers, to transplant into humans. 科学家们认为，与人类越发相像的物种，越适合作为药理毒性试验，或是用来培养人类器官用来移植。Watching how human cells mature and interact in a living creature may also lead to the discoveries of new medical treatments. 在活体上观察人体细胞的成熟以及相互影响，将把医疗技术带入一个新的领域。But creating human-animal chimeras—named after a monster in Greek mythology that had a lion’s head, goat’s body, and serpent’s tail—has raised troubling questions: What new subhuman combination should be produced and for what purpose? At what point would it be considered human? And what rights, if any, should it have?但是，这种被称为“奇美拉”（源自希腊神话的一种怪兽，有狮子的头、山羊的身体、蛇的尾巴）的人兽混合体，引发了一场争论：我们将制造出什么样的人兽混合体？这种生物可以算作人类吗？“它们”能有权利吗？There are currently no U.S. federal laws that address these issues. 现在美国的联邦法律还没有任何相关的条款。

Ethical Guidelines 道德界限The National Academy of Sciences, which advises the U.S. government, has been studying the issue. In March it plans to present voluntary ethical guidelines for researchers. 为美国政府提供咨询的国家科技协会已经开始研究这个问题。三月份该协会就会出台一个针对研究者们道德宣言。A chimera is a mixture of two or more species in one body. Not all are considered troubling, though. “奇美拉”作为多个物种的混合体，并不可以完全否定它。For example, faulty human heart valves are routinely replaced with ones taken from cows and pigs. The surgery—which makes the recipient a human-animal chimera—is widely accepted. And for years scientists have added human genes to bacteria and farm animals.例如心脏瓣膜手术中，将牛或猪的瓣膜移植给人。这种常见的外科手术造就的“奇美拉”是被广泛认同的，为此，科学家多年前就开始将人类基因植入动物细胞。What’s caused the uproar is the mixing of human stem cells with embryonic animals to create new species.真正引发争论的是将人类干细胞植入动物体内的做法，因为这样会制造出新的物种。Biotechnology activist Jeremy Rifkin is opposed to crossing species boundaries, because he believes animals have the right to exist without being tampered with or crossed with another species.著名的生物工艺学家JR坚决反对这种跨越物种的行为，他认为动物也有权利不受到其他物种的侵犯。He concedes that these studies would lead to some medical breakthroughs. Still, they should not be done.他承认这些行为能给医疗界带来突破，但是他仍然很反对。"There are other ways to advance medicine and human health besides going out into the strange, brave new world of chimeric animals," Rifkin said, adding that sophisticated computer models can substitute for experimentation on live animals.JR表示：“我们有很多的方法可以升级医学水平、促进人类健康，根本不用通过所谓的‘奇美拉’来达到目的。尖端电脑模型也可以帮助我们避免在大量活体上做试验”"One doesn’t have to be religious or into animal rights to think this doesn’t make sense," he continued. "It’s the scientists who want to do this. They’ve now gone over the edge into the pathological domain." “这不是所谓的宗教或权利问题了，有一些科学家已经变得太病态的在进行此项事业”David Magnus, director of the Stanford Center for Biomedical Ethics at Stanford University, believes the real worry is whether or not chimeras will be put to uses that are problematic, risky, or dangerous.斯坦福大学生物医学道德中心的主管DM认为，“奇美拉”投入实践环节是很冒险的，也是非常危险的。For example, an experiment that would raise concerns, he said, is genetically engineering mice to produce human sperm and eggs, then doing in vitro fertilization to produce a child whose parents are a pair of mice. 现在全球都在关注着用老鼠胚胎制造人类精子和卵子的基因实验，甚至尝试着制造出一个有老鼠父母的孩子。